A tap index and a thumb index have been heretofore known as indices for identifying contents described in documents, books and the like.
The tap index includes an index body formed of paper or plastics, and an adhesive portion formed by adhering glue onto one end of the index body. The tap index is pasted onto a desired page of a document through the adhesive portion so that the other end of the index body can protrude from an end of the document.
The tap index has the following drawbacks: (1) the tap index is pasted on only one page of the document, and accordingly, is unsuitable for identifying a plurality of pages (page group); (2) the tap index is pasted onto the desired page of the document so that the other end of the index body can protrude from the end of the document, and accordingly, the document including the tap index is difficult to be enclosed in an envelope or a file; and (3) the tap index is prone to be detached from the document when touching an external factor such as a finger of a user.
The thumb index is formed on an end portion of a desired page group of a book by a thumb punch 101 shown in FIG. 1. The thumb index is formed by directly cutting the end portion of the page group, and accordingly overcomes the drawbacks of the tap index, which are described above.
However, the thumb punch 101 is upsized in order to cut the end portion of the desired page group including a large number of pages at one time. Therefore, the thumb punch 101 has a wasted space in terms of cutting an end portion of a desired page group including a small number of pages or cutting an end portion of a desired page. Moreover, since the thumb punch 101 has, on a tip end thereof, a circular-arc cutting edge 103 exposed from the thumb punch 101, it is difficult for the user to carry the thumb punch 101 with easiness.